This question touches on a point of law. However, it does not seek legal advice about a specific situation: it is about general facts regarding the laws surrounding a class of situations.
Legal advice about specific situations is problematic and generally needs to be provided on a one-to-one basis within the context of a formal attorney-client relationship, especially in the United States.
Generalities about a point of law are a different matter. There is no reason to prohibit questions about the law, any more than we might prohibit questions about science or questions about language. It's a topic like any other topic, and it is sometimes relevant to moderation and community building.
The statement that “Stack Exchange cannot provide (…) legal advice” is a non sequitur. Stack Exchange isn't providing legal advice. A bunch of strangers with no particular credentials are making statements on a public forum. This does not remotely constitute any kind of attorney-client relationship and is not subject to any legal requirements.
There is no reason to single out legal considerations among other considerations. If legal considerations are relevant to an on-topic question, so be it. They don't somehow make the question off-topic.